Bug fixes in the API & standardisation for environment variable configurations

@remy, I deployed your master to my server, and all API requests stopped working.  If you look at my commit 1276644, you will see that I fixed the problem for API authenticated users when allowAnonymous is set to false.

I also fixed a bunch of other smaller issues, improved readability of the configuration for API settings.

Finally, in preparation for the Heroku branch to be landed and your comments about the code being littered with `process.env.VAR` references, in commit a97f5da I modified the config so that it automatically loads env vars prefixed with the JSBIN namespace.  This commit needs to land now before the Postgre and Heroku pull requests can land.